Help please, suspected cat failure (CLK)

[Birdman]

If it is over-fuelling it can't do the cats any good - that's what shortens its life quickest I believe.
I'm on 88K with original cats and at the last MOT had excellent emission readings so hoping to get well above 100K barring accidents.

 

[mrfwonderful200]

4 cats?

Having looked at the exploded diagram I can see 4 cats which is the same number as I have on my 1999 S320, though my exhast is 2 complete seperate systems. The 2 front cats are beside Nos 5 & 29, the rear cats are beside Nos 8 & 23!

 

[LeighW]

Just thought I'd update this thread. The fault (misfire, engine light on) reappeared for the first time last week. Again, it ran on only 3 cylinders, and the light was flashing. I switched it off, and it ran fine when restarted, but the light stayed on for a couple of days. Anyhow, as luck would have it, it was due a B service anyway, so I asked them to take a look at it while it was in. And it was diagnosed as... MAF failure. SO glad I didn't shell out over £1k to replace perfectly good cats.

I was quoted £215+vat for the MAF, so I told the MB dealer that I'd source my own (I was already facing a bill for the B service, plus replacement of both front balljoints & steering damper). I found one on ebay (brand new pattern part) for £49 delivered! The car runs as sweet as a nut now, it pulls sweetly to the redline which it never seemed to want to do before, and the gearbox is now changing as it should. Happy days!

 

[Birdman]

Brilliant - excellent outcome. You saved £1000, and then another £200 on the MAF. My understanding from the forum is that the mass airflow sensor is all too often the cause of these strange power-loss problems. How come the dealer didn't diagnose it at once with their STAR system?

 

[LeighW]

How come the dealer didn't diagnose it at once with their STAR system?

I have no idea. Fortunately, the last time it had shown the fault, it had been on the other bank of cylinders, so that ruled out the cat being at fault. The service manager (who I know) was on holiday when the cat was blamed, he told me he thought they'd diagnosed it wrongly, and he was right. That could have been a costly mistake - for me!! I assume it was diagnosed with STAR this time.

Anyhow, my trusty Merc has demonstrated it's superb build quality again today, the door check strap appears to have broken. The door made a loud 'crack' when I closed it, it now swings freely when I open it, and the window will only go half way down before jamming. Yay. But that's another story for another thread...

 

[Birdman]

Anyhow, my trusty Merc has demonstrated it's superb build quality again today, the door check strap appears to have broken. The door made a loud 'crack' when I closed it, it now swings freely when I open it, and the window will only go half way down before jamming. Yay. But that's another story for another thread...

My previous car, a W210 E320, had the driver's door check strap go too, although the car was still under warranty, and they simply resecured it. Maybe a fixing bolt/plate has dropped into the winding mechanism?
Come to think of it, a neighbour's W140 S-class had the exact same problem. He's elderly and the door gets used far more often than the kick-down for sure.

 

[Dieselman]

I had a Volvo some years ago and the check strap jammed and punched the mechanism into the door ripping the frame. Had a new door under warranty.

 

[Maddox5]

Have you tried the trusty Italian Tuneup method. Clears Cats a treat I understand !!

Make sure engine warm and topped up with oil first mind.

 

[television]

Can I just add a little on fault code reading, often in the case of a faulty MAF other fault codes will be thrown up as the other components have deviated from there stored settings to compensate, in most cases a code reader will throw up all kinds of codes,but never the MAF, its a matter of knowing what you are looking at.
Had a 129 in the limp home mode now and then. The fault codes thrown up were stupid,one time it threw up 28 Can BUS faults for just about everything on the car. looking at all of these codes I noticed that the gearbox ECU never came up, a check on the gearbox multi plug showed that there was a poor connection on the plug, on the two CAN BUS wires at the end. In 2 years and 20 visits MB could not find it.

Malcolm